Effect of Acceptor (Mg) Concentration on the Resistance Degradation Behavior in Acceptor (Mg)‐Doped BaTiO3 Bulk Ceramics: II. Thermally Stimulated Depolarization Current Analysis

Abstract

Thermally stimulated depolarization current (TSDC) of acceptor (Mg)‐doped BaTiO3 ceramics was analyzed with different acceptor concentrations for coarse‐grained specimens with uniform grain sizes. In all specimens, the increase of the polarization temperature (TP) for a fixed condition of polarization field (EP) and polarization time (tP) increased TSDC peak associated with an oxygen vacancy (VO••) relaxation. When the acceptor concentration is increased, both TP to generate same magnitude of TSDC and the relaxation temperature (Tm) of the TSDC peak systematically decreased. On the other hand, the activation energy of the oxygen vacancy relaxation showed roughly constant values of ∼0.9 eV, irrespective of acceptor concentration. Such behavior can be explained by a decrease in the relaxation time constant (τ0), which is in turn associated with the shape of oxygen vacancy profile in the specimen after polarization. The decrease of TP, Tm, τ0, and the little change of activation energy from the TSDC data with the increase of acceptor concentration implies an increase in the oxygen vacancy concentration C(VO••). The experimentally observed behavior of C(VO••) vs acceptor concentration could be explained by the defect chemical model, and from these results, the acceptor ionization energy EA was estimated to be about 1.0 eV.